[WIP] Allow scroll events to permanently change the default gesture handler in RootView

ash/frame/caption_buttons/frame_size_button.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ash/frame/caption_buttons/frame_size_button.h"
 
 #include "ash/metrics/user_metrics_recorder.h"
 #include "ash/screen_util.h"
 #include "ash/shell.h"
 #include "ash/touch/touch_uma.h"
@@ skipping 102 matching lines @@
 
   if (event->type() == ui::ET_GESTURE_SCROLL_BEGIN ||
       event->type() == ui::ET_GESTURE_SCROLL_UPDATE) {
     UpdateSnapType(*event);
     event->SetHandled();
     return;
   }
 
   if (event->type() == ui::ET_GESTURE_TAP ||
       event->type() == ui::ET_GESTURE_SCROLL_END ||
-      event->type() == ui::ET_SCROLL_FLING_START ||
-      event->type() == ui::ET_GESTURE_END) {

[tdresser, 2014/07/24 18:17:22]

This changes behavior, doesn't it?
Are we ok with the behavior change?

[sadrul, 2014/07/24 19:12:13]

Looks like the code starts doing things in response to TAP_DOWN and/or
SCROLL_BEGIN/UPDATE. So TAP_CANCEL and SCROLL_END should be sufficient for this.
It doesn't look like this View processes GESTURE_BEGIN event, so it shouldn't
need to do anything in response to GESTURE_END.

[tdresser, 2014/07/24 19:16:44]

Shouldn't it also listen to LONG_TAP?

[sadrul, 2014/07/24 19:21:34]

Good point. That will probably be necessary here, yes.

[tdanderson, 2014/07/25 17:16:10]

Thanks for pointing this out.

+      event->type() == ui::ET_SCROLL_FLING_START) {
     if (CommitSnap(*event)) {
       if (event->type() == ui::ET_GESTURE_TAP) {
         TouchUMA::GetInstance()->RecordGestureAction(
             TouchUMA::GESTURE_FRAMEMAXIMIZE_TAP);
       }
       event->SetHandled();
       return;
     }
   }
 
@@ skipping 140 matching lines @@
 void FrameSizeButton::SetButtonsToNormalMode(
     FrameSizeButtonDelegate::Animate animate) {
   in_snap_mode_ = false;
   snap_type_ = SNAP_NONE;
   set_buttons_to_snap_mode_timer_.Stop();
   delegate_->SetButtonsToNormal(animate);
   phantom_window_controller_.reset();
 }
 
 }  // namespace ash